Microwave-assisted Claisen rearrangement of naphthyl 2-propynyl ethers: synthesis of naphthofurans

An efficient two-step approach for the synthesis of naphtho[1,2-b]furans and naphtho[2,1-b]furans has been developed. Various functionalized propargyl alcohols were etherified with α- or β-naphthol under Mitsunobu reaction conditions to give naphthyl 2-propynyl ethers, which underwent a facile microwave-assisted Claisen rearrangement and concomitant anionic cyclization to yield naphthofuran derivatives under basic reaction conditions.